Methane Digesters

Practical Solution

The “How To”

According to the Minnesota Department of Agriculture, methane digesters, also known as anaerobic digesters, "collect manure and convert the energy stored in its organic matter into methane, which is used to produce energy... The conversion to methane is the result of anaerobic digestion- a biochemical process in which organic matter is decomposed by bacteria in the absence of oxygen." 

Methane digesters have numerous benefits, including producing renewable energy. They also improve air quality by reducing greenhouse gas emissions and odors from the manure. Methane digester owners can sell the energy generated and qualify for carbon credit paymers. The leftover manure is actually a better fertilizer for crops, and the manure can even be further processed into bedding for farm animials.

A feasibility study must be completed in order to identify a source and likely the quantity of inputs, anticipated volume of outputs, electric buy back rates, and end users for liquid and solid materials, nutrients, and liquefied petrolium (LP) gas. The study will identify which components of the system are feasible and which are not. A design phase would be the next step, followed by financing, construction, and operation.

USDA Natural Resources Conservation Service would be the government authority on this subject matter. 

Planning & Zoning

As methane digesters are generally sited in rural agricultural areas, and they reduce nutrient runoff and livestock odor, there are generally few planning and/or zoning requirements. Any issues would be identified within the feasibility study phase.

Dollars & Cents

There are far too many variables to provide a general economic summary. Electric buy-back rates in the mid-west are relatively low, and therefore other sources of income, such as tipping fees associated with co-substrates, or local use of the liquefied petroleum (LP) gas (vehicle fleets) is critical to making a methane digester feasible. While methane digesters are generally associated with animals, and specifically animal waste, they can also be successfully implemented in other industries where there is a large volume of waste.

SEaB Energy is a company that sells methane digesters, and they can provide further information on how to purchase one.

The Urban Farm Guys have an instructional video on how to make our own methane digester. Their digester is designed to handle manure generated by an individual, not a farm animal.

Measuring Success

Methane digesters will contribute to reducing greenhouse gas emissions for the region, measured by the total carbon dioxide equivalent emissions per capita. The 2010 baseline was 21.10 mtC02e, and the desired trend is for this number to go down.

Case Studies

Anaerobic Digestion at Morrisville State College

• Contact

  Walid Shayya
  Professor
  315-684-6526
  This email address is being protected from spambots. You need JavaScript enabled to view it.

  Description

  To learn more about this project, click here. 

  Cost $0

  Lessons Learned

  https://www.morrisville.edu/arnold-r-fisher-dairy-complex

Scenic View Dairy

• Contact

  Norma McDonald
  North America Manager, Organic Water Systems
  513-535-6760
  This email address is being protected from spambots. You need JavaScript enabled to view it.

  Description

  The Scenic View Dairy is a dairy farm in Fennville, MI, that houses approximately 2200 head of cattle. Prior to the installation of the anaerobic digester, Scenic View utilized sand for animal bedding which has now been 100% replaced by the separated digested biofibers, which are 99.9% sanitized and virtually odor free. The methane produced from this system is also of excellent quality (60%) that is utilized in eclectic generators for one-farm use as well as sold to the power grid for the use of the community. This farm will be the first in the world to combine electricity generation with biogas upgrading to pipeline standards, providing a second option for revenue optimization. The reduction in methane emissions resulting from the digestion process, as well as emission offsets for the replacement of fossil fuels, will be converted to carbon equivalents, and traded on the Chicago Climate Exchange for additional revenue. 

  Cost $0

Discover More

Additional information about methane digesters can be found from Purdue University's Basics of Energy Production through Anaerobic Digestion of Livestock Manure and from the Midwest Rural Energy Council.